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Edwards T, Bouyoucos IA, Hasler CT, Fry M, Anderson WG. Understanding olfactory and behavioural responses to dietary cues in age-1 lake sturgeon Acipenser fulvescens. Comp Biochem Physiol A Mol Integr Physiol 2024; 288:111560. [PMID: 38056556 DOI: 10.1016/j.cbpa.2023.111560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Revised: 12/01/2023] [Accepted: 12/01/2023] [Indexed: 12/08/2023]
Abstract
Detection of environmental cues is essential for all vertebrates and is typically established by the olfactory epithelium and olfactory sensory neurons (OSNs). In fishes, microvillous and ciliated OSNs are the principal types, typically detecting amino acids and bile salts, respectively. Activation of OSN receptors by specific ligands initiate downstream signal processing often leading to behavioural responses. In this study we used electrophysiological and behavioural techniques to evaluate olfactory detection and behaviour in juvenile lake sturgeon Acipenser fulvescens in response to hatchery- and natural dietary cues. We hypothesized that electro-olfactogram (EOG) and behavioural responses would be dependent on diet type. We predicted that inhibition of the phospholipase C/inositol 1,4,5-triphosphate (PLC/IP3) secondary transduction pathway would reduce EOG responses to dietary cues and, inhibition of the adenylyl cyclase/adenosine 3,5-cyclic monophosphate (cAMP) pathway, would have no effect. Furthermore, we predicted a strong EOG response would be manifested in a change in behaviour. We observed that both the PLC/IP3 and cAMP pathways were significantly involved in the detection of dietary cues. However, EOG responses did not manifest to behavioural responses, although the foraging activity to the hatchery cue was significantly greater compared to the control. Our results support the notion that lake sturgeon raised in a hatchery and fed a commercial pelleted diet may become accustomed to it prior to release into the wild. Further, this study suggests that, in conservation aquaculture settings, lake sturgeon should be exposed to natural dietary cues prior to release as one strategy to promote food recognition.
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Affiliation(s)
- Tyler Edwards
- University of Manitoba, Department of Biological Sciences, 50 Sifton Road Winnipeg, Manitoba R3T 2N2, Canada.
| | - Ian A Bouyoucos
- University of Manitoba, Department of Biological Sciences, 50 Sifton Road Winnipeg, Manitoba R3T 2N2, Canada
| | - Caleb T Hasler
- The University of Winnipeg, Department of Biology, 515 Portage Ave Winnipeg, Manitoba R3B 2E9, Canada
| | - Mark Fry
- University of Manitoba, Department of Biological Sciences, 50 Sifton Road Winnipeg, Manitoba R3T 2N2, Canada
| | - W Gary Anderson
- University of Manitoba, Department of Biological Sciences, 50 Sifton Road Winnipeg, Manitoba R3T 2N2, Canada
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2
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Bettini S, Lazzari M, Milani L, Maurizii MG, Franceschini V. Immunohistochemical Analysis of Olfactory Sensory Neuron Populations in the Developing Olfactory Organ of the Guppy, Poecilia reticulata (Cyprinodontiformes, Poecilidae). MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2023; 29:1764-1773. [PMID: 37639707 DOI: 10.1093/micmic/ozad099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 07/11/2023] [Accepted: 08/14/2023] [Indexed: 08/31/2023]
Abstract
Olfaction is fundamental for sensing environmental chemicals and has obvious adaptive advantages. In fish, the peripheral olfactory organ is composed of lamellae in which the olfactory mucosa contains three main categories of olfactory sensory neurons (OSNs) as follows: ciliated (cOSNs), microvillous (mOSNs), and crypt cells. We studied the appearance of these different OSNs during development of Poecilia reticulata, given its growing use as animal model system. We performed immunohistochemical detection of molecular markers specific for the different OSNs, carrying out image analyses for marked-cell counting and measuring optical density. The P. reticulata olfactory organ did not show change in size during the first weeks of life. The proliferative activity increased at the onset of secondary sexual characters, remaining high until sexual maturity. Then, it decreased in both sexes, but with a recovery in females, probably in relation to their almost double body growth, compared to males. The density of both cOSNs and mOSNs remained constant throughout development, probably due to conserved functions already active in the fry, independently of the sex. The density of calretinin-positive crypt cells decreased progressively until sexual maturity, whereas the increased density of calretinin-negative crypt cell fraction, prevailing in later developmental stages, indicated their probable involvement in reproductive activities.
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Affiliation(s)
- Simone Bettini
- Department of Biological, Geological and Environmental Sciences, University of Bologna, Via Selmi 3, 40126 Bologna, Italy
| | - Maurizio Lazzari
- Department of Biological, Geological and Environmental Sciences, University of Bologna, Via Selmi 3, 40126 Bologna, Italy
| | - Liliana Milani
- Department of Biological, Geological and Environmental Sciences, University of Bologna, Via Selmi 3, 40126 Bologna, Italy
| | - Maria Gabriella Maurizii
- Department of Biological, Geological and Environmental Sciences, University of Bologna, Via Selmi 3, 40126 Bologna, Italy
| | - Valeria Franceschini
- Department of Biological, Geological and Environmental Sciences, University of Bologna, Via Selmi 3, 40126 Bologna, Italy
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3
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Velez Z, Costa RA, Wang W, Hubbard PC. Independent effects of seawater pH and high P CO2 on olfactory sensitivity in fish: possible role of carbonic anhydrase. J Exp Biol 2021; 224:jeb.238485. [PMID: 33658240 DOI: 10.1242/jeb.238485] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 02/08/2021] [Indexed: 11/20/2022]
Abstract
Ocean acidification may alter olfactory-driven behaviour in fish by direct effects on the peripheral olfactory system; olfactory sensitivity is reduced in CO2-acidified seawater. The current study tested whether this is due to elevated P CO2 or the consequent reduction in seawater pH and, if the former, the possible involvement of carbonic anhydrase, the enzyme responsible for the hydration of CO2 and production of carbonic acid. Olfactory sensitivity to amino acids was assessed by extracellular multi-unit recording from the olfactory nerve of the gilthead seabream (Sparus aurat a L.) in normal seawater (pH ∼8.2), and after acute exposure to acidified seawater (pH ∼7.7) but normal P CO2 (∼340 µatm) or to high P CO2 seawater (∼1400 µatm) at normal pH (∼8.2). Reduced pH in the absence of elevated P CO2 caused a reduction in olfactory sensitivity to l-serine, l-leucine, l-arginine and l-glutamine, but not l-glutamic acid. Increased P CO2 in the absence of changes in pH caused reduced olfactory sensitivity to l-serine, l-leucine and l-arginine, including increases in their threshold of detection, but had no effect on sensitivity to l-glutamine and l-glutamic acid. Inclusion of 1 mmol l-1 acetazolamide (a membrane-permeant inhibitor of carbonic anhydrase) in the seawater reversed the inhibition of olfactory sensitivity to l-serine caused by high P CO2 Ocean acidification may reduce olfactory sensitivity by reductions in seawater pH and intracellular pH (of olfactory receptor neurones); the former by reducing odorant-receptor affinity, and the latter by reducing the efficiency of olfactory transduction. The physiological role of carbonic anhydrase in the olfactory receptor neurones remains to be explored.
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Affiliation(s)
- Zélia Velez
- Centro de Ciências do Mar, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Rita A Costa
- Centro de Ciências do Mar, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Wenjing Wang
- Centro de Ciências do Mar, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Peter C Hubbard
- Centro de Ciências do Mar, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
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4
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Camilieri-Asch V, Caddy HT, Hubbard A, Rigby P, Doyle B, Shaw JA, Mehnert A, Partridge JC, Yopak KE, Collin SP. Multimodal Imaging and Analysis of the Neuroanatomical Organization of the Primary Olfactory Inputs in the Brownbanded Bamboo Shark, Chiloscyllium punctatum. Front Neuroanat 2020; 14:560534. [PMID: 33324175 PMCID: PMC7726474 DOI: 10.3389/fnana.2020.560534] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Accepted: 09/23/2020] [Indexed: 11/22/2022] Open
Abstract
There is currently a limited understanding of the morphological and functional organization of the olfactory system in cartilaginous fishes, particularly when compared to bony fishes and terrestrial vertebrates. In this fish group, there is a clear paucity of information on the characterization, density, and distribution of olfactory receptor neurons (ORNs) within the sensory olfactory epithelium lining the paired olfactory rosettes, and their functional implications with respect to the hydrodynamics of incurrent water flow into the nares. This imaging study examines the brownbanded bamboo shark Chiloscyllium punctatum (Elasmobranchii) and combines immunohistochemical labeling using antisera raised against five G-protein α-subunits (Gαs/olf, Gαq/11/14, Gαi–1/2/3, Gαi–3, Gαo) with light and electron microscopy, to characterize the morphological ORN types present. Three main ORNs (“long”, “microvillous” and “crypt-like”) are confirmed and up to three additional microvilli-bearing types are also described; “Kappe-like” (potential or homologous “Kappe” as in teleosts), “pear-shaped” and “teardrop-shaped” cells. These morphotypes will need to be confirmed molecularly in the future. Using X-ray diffusible iodine-based contrast-enhanced computed tomography (diceCT), high-resolution scans of the olfactory rosettes, olfactory bulbs (OBs), peduncles, and telencephalon reveal a lateral segregation of primary olfactory inputs within the OBs, with distinct medial and lateral clusters of glomeruli, suggesting a potential somatotopic organization. However, most ORN morphotypes are found to be ubiquitously distributed within the medial and lateral regions of the olfactory rosette, with at least three microvilli-bearing ORNs labeled with anti-Gαo found in significantly higher densities in lateral lamellae [in lateral lamellae] and on the anterior portion of lamellae (facing the olfactory cavity). These microvilli-bearing ORN morphotypes (microvillous, “Kappe-like,” “pear-shaped,” and “teardrop-shaped”) are the most abundant across the olfactory rosette of this species, while ciliated ORNs are less common and crypt cells are rare. Spatial simulations of the fluid dynamics of the incurrent water flow into the nares and within the olfactory cavities indicate that the high densities of microvilli-bearing ORNs located within the lateral region of the rosette are important for sampling incoming odorants during swimming and may determine subsequent tracking behavior.
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Affiliation(s)
- Victoria Camilieri-Asch
- School of Biological Sciences, The University of Western Australia, Perth, WA, Australia.,The Neuroecology Group, UWA Oceans Institute, The University of Western Australia, Perth, WA, Australia
| | - Harrison T Caddy
- Vascular Engineering Laboratory, Centre for Medical Research, Harry Perkins Institute of Medical Research, The University of Western Australia, Perth, WA, Australia.,School of Engineering, The University of Western Australia, Perth, WA, Australia
| | - Alysia Hubbard
- Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Perth, WA, Australia
| | - Paul Rigby
- Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Perth, WA, Australia
| | - Barry Doyle
- Vascular Engineering Laboratory, Centre for Medical Research, Harry Perkins Institute of Medical Research, The University of Western Australia, Perth, WA, Australia.,School of Engineering, The University of Western Australia, Perth, WA, Australia.,Australian Research Council Centre for Personalised Therapeutics Technologies, Perth, WA, Australia.,BHF Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, United Kingdom
| | - Jeremy A Shaw
- Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Perth, WA, Australia
| | - Andrew Mehnert
- Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Perth, WA, Australia.,National Imaging Facility, Brisbane, QLD, Australia
| | - Julian C Partridge
- The Neuroecology Group, UWA Oceans Institute, The University of Western Australia, Perth, WA, Australia
| | - Kara E Yopak
- Department of Biology and Marine Biology, Center for Marine Science, University of North Carolina Wilmington, Wilmington, NC, United States
| | - Shaun P Collin
- The Neuroecology Group, UWA Oceans Institute, The University of Western Australia, Perth, WA, Australia.,School of Life Sciences, La Trobe University, Melbourne, VIC, Australia
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5
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Olivares J, Schmachtenberg O. An update on anatomy and function of the teleost olfactory system. PeerJ 2019; 7:e7808. [PMID: 31579633 PMCID: PMC6768218 DOI: 10.7717/peerj.7808] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 09/01/2019] [Indexed: 12/16/2022] Open
Abstract
About half of all extant vertebrates are teleost fishes. Although our knowledge about anatomy and function of their olfactory systems still lags behind that of mammals, recent advances in cellular and molecular biology have provided us with a wealth of novel information about the sense of smell in this important animal group. Its paired olfactory organs contain up to five types of olfactory receptor neurons expressing OR, TAAR, VR1- and VR2-class odorant receptors associated with individual transduction machineries. The different types of receptor neurons are preferentially tuned towards particular classes of odorants, that are associated with specific behaviors, such as feeding, mating or migration. We discuss the connections of the receptor neurons in the olfactory bulb, the differences in bulbar circuitry compared to mammals, and the characteristics of second order projections to telencephalic olfactory areas, considering the everted ontogeny of the teleost telencephalon. The review concludes with a brief overview of current theories about odor coding and the prominent neural oscillations observed in the teleost olfactory system.
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Affiliation(s)
- Jesús Olivares
- Centro Interdisciplinario de Neurociencia de Valparaíso (CINV), Universidad de Valparaíso, Valparaíso, Chile.,Universidad de Valparaíso, PhD Program in Neuroscience, Valparaíso, Chile
| | - Oliver Schmachtenberg
- Centro Interdisciplinario de Neurociencia de Valparaíso (CINV), Universidad de Valparaíso, Valparaíso, Chile
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6
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Sato K, Sorensen PW. The Chemical Sensitivity and Electrical Activity of Individual Olfactory Sensory Neurons to a Range of Sex Pheromones and Food Odors in the Goldfish. Chem Senses 2018; 43:249-260. [PMID: 29514213 PMCID: PMC5913646 DOI: 10.1093/chemse/bjy016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Although it is well established that the olfactory epithelium of teleost fish detects at least 6 classes of biologically relevant odorants using 5 types of olfactory sensory neurons (OSNs), little is understood about the specificity of individual OSNs and thus how they encode identity of natural odors. In this study, we used in vivo extracellular single-unit recording to examine the odor responsiveness and physiological characteristics of 109 individual OSNs in mature male goldfish to a broad range of biological odorants including feeding stimuli (amino acids, polyamines, nucleotides), sex pheromones (sex steroids, prostaglandins [PGs]), and a putative social cue (bile acids). Sixty-one OSNs were chemosensitive, with over half of these (36) responding to amino acids, 7 to polyamines, 7 to nucleotides, 5 to bile acids, 9 to PGs, and 7 to sex steroids. Approximately a quarter of the amino acid-sensitive units also responded to polyamines or nucleotides. Three of 6 amino acid-sensitive units responded to more than 1 amino acid compound, and 5 sex pheromone-sensitive units detected just 1 sex pheromone. While pheromone-sensitive OSNs also responded to the adenylyl cyclase activator, forskolin, amino acid-sensitive OSNs responded to either forskolin or a phospholipase C activator, imipramine. Most OSNs responded to odorants and activators with excitation. Our results suggest that pheromone information is encoded by OSNs specifically tuned to single sex pheromones and employ adenylyl cyclase, suggestive of a labeled-line organization, while food information is encoded by a combination of OSNs that use both adenylyl cyclase and phospholipase C and are often less specifically tuned.
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Affiliation(s)
- Koji Sato
- Okazaki Institute for Integrative Bioscience, Biosensing Research, Higashiyama Myodaijicho, Okazaki, Aichi, Japan
| | - Peter W Sorensen
- Department of Fisheries, Wildlife and Conservation Biology, University of Minnesota, St Paul, MN, USA
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Assaying sensory ciliopathies using calcium biosensor expression in zebrafish ciliated olfactory neurons. Cilia 2018; 7:2. [PMID: 29568513 PMCID: PMC5856005 DOI: 10.1186/s13630-018-0056-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Accepted: 02/22/2018] [Indexed: 12/12/2022] Open
Abstract
Background Primary cilia mediate signal transduction by acting as an organizing scaffold for receptors, signalling proteins and ion channels. Ciliated olfactory sensory neurons (OSNs) organize olfactory receptors and ion channels on cilia and generate a calcium influx as a primary signal in odourant detection. In the zebrafish olfactory placode, ciliated OSNs and microvillus OSNs constitute the major OSN cell types with distinct odourant sensitivity. Methods Using transgenic expression of the calcium biosensor GCaMP5 in OSNs, we analysed sensory cilia-dependent odour responses in live zebrafish, at individual cell resolution. oval/ift88 mutant and ift172 knockdown zebrafish were compared with wild-type siblings to establish ciliated OSN sensitivity to different classes of odourants. Results oval/ift88 mutant and ift172 knockdown zebrafish showed fewer and severely shortened OSN cilia without a reduction in OSN number. The fraction of responding OSNs and response amplitudes to bile acids and food odour, both sensed by ciliated OSNs, were significantly reduced in ift88 mutants and ift172-deficient embryos, while the amino acids responses were not significantly changed. Conclusions Our approach presents a quantitative model for studying sensory cilia signalling using zebrafish OSNs. Our results also implicate ift172-deficiency as a novel cause of hyposmia, a reduced sense of smell, highlighting the value of directly assaying sensory cilia signalling in vivo and supporting the idea that hyposmia can be used as a diagnostic indicator of ciliopathies. Electronic supplementary material The online version of this article (10.1186/s13630-018-0056-1) contains supplementary material, which is available to authorized users.
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8
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Crypt cells are involved in kin recognition in larval zebrafish. Sci Rep 2016; 6:24590. [PMID: 27087508 PMCID: PMC4834543 DOI: 10.1038/srep24590] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 04/01/2016] [Indexed: 12/18/2022] Open
Abstract
Zebrafish larvae imprint on visual and olfactory kin cues at day 5 and 6 postfertilization, respectively, resulting in kin recognition later in life. Exposure to non-kin cues prevents imprinting and kin recognition. Imprinting depends on MHC class II related signals and only larvae sharing MHC class II alleles can imprint on each other. Here, we analyzed which type of olfactory sensory neuron (OSN) detects kin odor. The single teleost olfactory epithelium harbors ciliated OSNs carrying OR and TAAR gene family receptors (mammals: main olfactory epithelium) and microvillous OSNs with V1R and V2R gene family receptors (mammals: vomeronasal organ). Additionally, teleosts exhibit crypt cells which possess microvilli and cilia. We used the activity marker pERK (phosphorylated extracellular signal regulated kinase) after stimulating 9 day old zebrafish larvae with either non-kin conspecific or food odor. While food odor activated both ciliated and microvillous OSNs, only the latter were activated by conspecific odor, crypt cells showed no activation to both stimuli. Then, we tested imprinted and non-imprinted larvae (full siblings) for kin odor detection. We provide the first direct evidence that crypt cells, and likely a subpopulation of microvillous OSNs, but not ciliated OSNs, play a role in detecting a kin odor related signal.
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9
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Osorio R, Schmachtenberg O. Calcium-activated chloride channels do not contribute to the odorant transduction current in the marine teleost Isacia conceptionis. JOURNAL OF FISH BIOLOGY 2013; 83:1468-1473. [PMID: 24580677 DOI: 10.1111/jfb.12253] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2013] [Accepted: 09/11/2013] [Indexed: 06/03/2023]
Abstract
This study compared the contribution of the Ca²⁺-activated Cl⁻ conductance to the electroolfactogram (EOG) evoked by different odorant classes between the marine Cabinza grunt Isacia conceptionis and rainbow trout Oncorhynchus mykiss. The Ca²⁺-activated Cl⁻ channel blocker niflumic acid significantly diminished odorant responses in O. mykiss, but had no effect on the EOG in I. conceptionis, supporting the notion that Ca²⁺-activated Cl⁻ channels may not operate as odorant transduction current amplifiers in this marine teleost.
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Affiliation(s)
- R Osorio
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Avda. Gran Bretaña 1111, 2360102, Valparaíso, Chile
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10
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Kermen F, Franco LM, Wyatt C, Yaksi E. Neural circuits mediating olfactory-driven behavior in fish. Front Neural Circuits 2013; 7:62. [PMID: 23596397 PMCID: PMC3622886 DOI: 10.3389/fncir.2013.00062] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 03/18/2013] [Indexed: 11/13/2022] Open
Abstract
The fish olfactory system processes odor signals and mediates behaviors that are crucial for survival such as foraging, courtship, and alarm response. Although the upstream olfactory brain areas (olfactory epithelium and olfactory bulb) are well-studied, less is known about their target brain areas and the role they play in generating odor-driven behaviors. Here we review a broad range of literature on the anatomy, physiology, and behavioral output of the olfactory system and its target areas in a wide range of teleost fish. Additionally, we discuss how applying recent technological advancements to the zebrafish (Danio rerio) could help in understanding the function of these target areas. We hope to provide a framework for elucidating the neural circuit computations underlying the odor-driven behaviors in this small, transparent, and genetically amenable vertebrate.
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Affiliation(s)
- Florence Kermen
- Neuroelectronics Research Flanders Leuven, Belgium ; Vlaams Instituut voor Biotechnologie Leuven, Belgium
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11
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Properties, projections, and tuning of teleost olfactory receptor neurons. J Chem Ecol 2013; 39:451-64. [PMID: 23468224 DOI: 10.1007/s10886-013-0268-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Revised: 12/17/2012] [Accepted: 02/01/2013] [Indexed: 10/27/2022]
Abstract
In many fishes, the olfactory sense participates in such vital processes as feeding, reproduction, orientation, and predator avoidance. In teleosts, these tasks are fulfilled by a single type of olfactory organ for odorant and pheromone detection, containing ciliated and microvillus receptor neurons, and olfactory crypt cells. Recently, progress was made in understanding crypt cell function with the discovery of a V1R-like odorant receptor expressed in this neuron, an analysis of crypt cell odorant tuning properties, and the dissection of crypt cell connectivity within the telecephalon. Here, we review recent findings on the molecular properties, functions, and associated neural pathways of the three types of teleost olfactory receptor neurons with special emphasis on the crypt cell, and evaluate their roles in the detection of food, social and sexual odorants.
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12
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Hassenklöver T, Pallesen LP, Schild D, Manzini I. Amino acid- vs. peptide-odorants: responses of individual olfactory receptor neurons in an aquatic species. PLoS One 2012; 7:e53097. [PMID: 23300867 PMCID: PMC3531423 DOI: 10.1371/journal.pone.0053097] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Accepted: 11/23/2012] [Indexed: 12/17/2022] Open
Abstract
Amino acids are widely used waterborne olfactory stimuli proposed to serve as cues in the search for food. In natural waters the main source of amino acids is the decomposition of proteins. But this process also produces a variety of small peptides as intermediate cleavage products. In the present study we tested whether amino acids actually are the natural and adequate stimuli for the olfactory receptors they bind to. Alternatively, these olfactory receptors could be peptide receptors which also bind amino acids though at lower affinity. Employing calcium imaging in acute slices of the main olfactory epithelium of the fully aquatic larvae of Xenopus laevis we show that amino acids, and not peptides, are more effective waterborne odorants.
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Affiliation(s)
- Thomas Hassenklöver
- Department of Neurophysiology and Cellular Biophysics, University of Göttingen, Göttingen, Germany
- Cluster of Excellence “Nanoscale Microscopy and Molecular Physiology of the Brain” (CNMPB), University of Göttingen, Göttingen, Germany
| | - Lars P. Pallesen
- Department of Neurophysiology and Cellular Biophysics, University of Göttingen, Göttingen, Germany
| | - Detlev Schild
- Department of Neurophysiology and Cellular Biophysics, University of Göttingen, Göttingen, Germany
- Cluster of Excellence “Nanoscale Microscopy and Molecular Physiology of the Brain” (CNMPB), University of Göttingen, Göttingen, Germany
| | - Ivan Manzini
- Department of Neurophysiology and Cellular Biophysics, University of Göttingen, Göttingen, Germany
- Cluster of Excellence “Nanoscale Microscopy and Molecular Physiology of the Brain” (CNMPB), University of Göttingen, Göttingen, Germany
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13
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Bazáes A, Schmachtenberg O. Odorant tuning of olfactory crypt cells from juvenile and adult rainbow trout. ACTA ACUST UNITED AC 2012; 215:1740-8. [PMID: 22539741 DOI: 10.1242/jeb.067264] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Teleost fish lack independent olfactory organs for odorant and pheromone detection. Instead, they have a single sensory epithelium with two populations of receptor neurons, ciliated and microvillous, that are conserved among vertebrates, and a unique receptor cell type named the olfactory crypt cell. Crypt cells were shown to be chemosensory neurons that project to specific areas in the olfactory bulb, but their odorant tuning and overall function remain unclear. Reproduction in fish is generally synchronized by sex pheromonal signaling between males and females, but the sensors responsible for pheromone detection remain unknown. In crucian carp, a seasonal variation in the population of olfactory crypt cells and their brain projections pathways, involved in reproduction, led to the hypothesis of a role as sex pheromone detectors. In the present study, morphology and localization of olfactory crypt cells were compared between juvenile and mature rainbow trout of both sexes, and calcium imaging was used to visualize responses of crypt cells from the three groups to common social and food-related odorants, sex hormones and conspecific tissue extracts. Crypt cells from mature trout were found to be larger than those of juvenile specimens, and preferentially localized to the apical surface of the olfactory epithelium. Although a fraction of crypt cells of all groups responded to common odorants such as amino acids and bile salts, cells from mature trout showed a characteristic preference for gonadal extracts and hormones from the opposite sex. These results support an involvement of olfactory crypt cells in reproduction-related olfactory signaling in fishes.
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Affiliation(s)
- Alejandra Bazáes
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Avda Gran Bretaña 1111, 2360102 Playa Ancha, Valparaíso, Chile
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14
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Vielma A, Ardiles A, Delgado L, Schmachtenberg O. The elusive crypt olfactory receptor neuron: evidence for its stimulation by amino acids and cAMP pathway agonists. ACTA ACUST UNITED AC 2008; 211:2417-22. [PMID: 18626075 DOI: 10.1242/jeb.018796] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Crypt olfactory receptor neurons (ORNs) are a third type of chemosensory neuron along with ciliated and microvillous ORNs in the olfactory epithelium of fishes, but their functional role is still unknown. To investigate their odorant response properties and possible transduction pathways, we recorded crypt ORN activity with calcium imaging and the patch clamp technique in its cell-attached mode in combination with odorant and agonist stimulation. Bile salts and putative fish pheromones did not elicit responses with either method, but the cells frequently responded to amino acids, with excitation and intracellular calcium signals. 8Br-cAMP and IBMX plus forskolin stimulated over 40% of crypt ORNs and triggered calcium signals in a similar percentage. Furthermore, crypt ORNs were immunoreactive to an antiserum against adenylate cyclase III. Together, these data suggest the presence of a cAMP transduction pathway, which might transduce odorants such as amino acids.
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Affiliation(s)
- Alex Vielma
- Centro de Neurociencia de Valparaíso, Universidad de Valparaíso, Avda. Gran Bretaña 1111, Casilla 5029, Correo 4 2360102 Valparaíso, Chile
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Nikonov AA, Caprio J. Highly specific olfactory receptor neurons for types of amino acids in the channel catfish. J Neurophysiol 2007; 98:1909-18. [PMID: 17686913 DOI: 10.1152/jn.00548.2007] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Odorant specificity to l-alpha-amino acids was determined electrophysiologically for 93 single catfish olfactory receptor neurons (ORNs) selected for their narrow excitatory molecular response range (EMRR) to only one type of amino acid (i.e., Group I units). These units were excited by either a basic amino acid, a neutral amino acid with a long side chain, or a neutral amino acid with a short side chain when tested at 10(-7) to 10(-5) M. Stimulus-induced inhibition, likely for contrast enhancement, was primarily observed in response to the types of amino acid stimuli different from that which activated a specific ORN. The high specificity of single Group I ORNs to type of amino acid was also previously observed for single Group I neurons in both the olfactory bulb and forebrain of the same species. These results indicate that for Group I neurons olfactory information concerning specific types of amino acids is processed from receptor neurons through mitral cells of the olfactory bulb to higher forebrain neurons without significant alteration in unit odorant specificity.
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Affiliation(s)
- Alexander A Nikonov
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
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Schmachtenberg O. Histological and electrophysiological properties of crypt cells from the olfactory epithelium of the marine teleost Trachurus symmetricus. J Comp Neurol 2006; 495:113-21. [PMID: 16432906 DOI: 10.1002/cne.20847] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Crypt cells from the olfactory epithelium of the Pacific jack mackerel Trachurus symmetricus were characterized by light and electron microscopy and analyzed in dissociation with the patch-clamp technique in its cell-attached, perforated patch and normal whole-cell mode. Isolated crypt cells remained united with their supporting cells, and both were electrically coupled through gap junctions. Under voltage-clamp, depolarizing voltage steps triggered a transient sodium current, a sustained calcium current, and two types of potassium currents with fast and slow inactivation kinetics. No calcium-dependent potassium current could be observed. The sodium current was blocked by saxitoxin, the calcium current by cobalt and furnidipine, and the potassium currents by tetraethylammonium chloride. In the cell-attached configuration, crypt cells displayed spontaneous spike activity and responded to amino acid solutions with dose-dependent excitation, followed by a period of spike inhibition. These first recordings of individual crypt cells provide the basis for future studies of their odorant specificity, transduction mechanism, and overall function in the fish olfactory epithelium.
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Affiliation(s)
- Oliver Schmachtenberg
- Centro de Neurociencias de Valparaiso CNV, Facultad de Ciencias, Universidad de Valparaiso, Valparaiso, Chile.
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